Trying to help my brother.

**lewisb13** · March 5th 2009, 04:14 AM

I am a seasoned mech eng and for whatever reason this problem is kicking my butt. Here goes.

Find the smallest integer X so that 252*X is a perfect cube.

Ok so you say y^3=252*X and thats as far as I got. Cant take derivatives since this is just trig, so Im stumped. Please help.

**puzzledwithpolynomials** · March 5th 2009, 05:13 AM

I read the question improperly - my bad. :P

**CaptainBlack** · March 5th 2009, 05:16 AM

Originally Posted by lewisb13

I am a seasoned mech eng and for whatever reason this problem is kicking my butt. Here goes.

Find the smallest integer X so that 252*X is a perfect cube.

Ok so you say y^3=252*X and thats as far as I got. Cant take derivatives since this is just trig, so Im stumped. Please help.

$252=2^2 3^2 7$

For $x \times 252$ to be a perfect cube every prime factor in its prime decomposition must appear with power $3$ . So $x=2 \times 3 \times 7^2$ is the smallest positive integer $x$ that makes $x \times 252$ a perfect cube.

CB

**lewisb13** · March 5th 2009, 05:18 AM

Man thank you so much. That seems like some pretty advanced stuff to me. Geez.

**puzzledwithpolynomials** · March 5th 2009, 05:21 AM

10char

Thread: Trying to help my brother.

LinkBack

Thread Tools

Display

Trying to help my brother.

Similar Math Help Forum Discussions

Statistic Problem based on Pokemon Game for litte brother

select a committie with brother and sister

Help A brother please!

Challenging Question - help a brother

Search Tags